As a prior art technique involving the use of zirconium oxide as a piezoelectric/electrostriction type element there is disclosed a piezoelectric/electrostriction type element obtained by employing a film formation process to form a piezoelectric/electrostriction working part on a zirconium oxide substrate as a ceramic substrate at an area having a reduced thickness in JP-A-6-204580 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). The zirconium oxide to be used as a substrate for this element comprises at least one compound selected from the group consisting of yttrium oxide, cerium oxide, magnesium oxide and calcium oxide incorporated therein to have a fully or partially stabilized crystal phase. Further, since a ceramic substrate is used, the area having a reduced thickness has a relatively great dimension or thickness.
As a prior art technique involving the use of a single-crystal silicon as a substrate there is disclosed in U.S. Pat. No. 5,265,315 a printer head for ink jet recording having a laminated structure comprising a metal barrier layer made of platinum (Pt) or nickel (Ni), an aluminum oxide layer, a lower electrode, a binary lead zirconate titanate (PZT) layer, and an upper electrode provided on a single-crystal silicon substrate at an area having a reduced thickness. This printer head for ink jet recording comprises a binary PZT. Thus, heat treatment is effected at a temperature of from 600.degree. C. to 650.degree. C.
However, the printer heads for ink jet recording according to the foregoing prior art techniques have the following disadvantages.
The piezoelectric/electrostriction type element described in JP-A-6-204580 comprises a ceramic substrate. In the case where this piezoelectric/electrostriction type element is used to form a printer head for ink jet recording, it is difficult to reduce the dimension or thickness of the thinner portion formed by the ceramic substrate. In fact, the thinner portion of the element disclosed in the above cited patent has a dimension of 0.8 mm.times.3 mm and a thickness of 10 .mu.m. The dimension of the thinner portion corresponds to the dimension of the ink chamber of the printer head for ink jet recording. In order to perform ink injection to a precision such that the density of nozzles on the printer head for ink jet recording is about 180 dpi, it is necessary that the thinner portion have a dimension of about 0.1 mm.times.4 mm and a thickness of about 1 .mu.m. Accordingly, such a fine structure cannot be formed by the element described in the above cited patent. Further, since a ceramic substrate is expensive, the printer head for ink jet recording prepared from the element described in the above cited patent is expensive.
The printer head for ink jet recording described in the above cited U.S. Pat. No. 5,265,315 comprises a piezoelectric layer made of a binary PZT. Since this piezoelectric layer exhibits an insufficient piezoelectricity, no products having satisfactory ink jetting properties can be obtained. In order to further enhance the piezoelectricity of the piezoelectric layer, it is desirable to use a ternary PZT containing a third component in an amount of not less than 5 mol %. However, in order to provide this piezoelectric thin film with almost the same properties as PZT of bulk ceramics, it is necessary that the calcining temperature of PZT be raised to 800.degree. C. However, if high temperature heat treatment is effected in the arrangement disclosed in the above cited U.S. patent, the vibrating plate portion can crack.
For the purpose of solving the foregoing problems, the inventors made extensive studies to develop an inexpensive durable printer head for ink jet recording having a smaller dimension and thickness of thinner portion which can be prepared without being subject to crack on the vibrating plate or the like even by a process which comprises high temperature heat treatment of a ternary PZT. As a result, it was found that by providing a zirconium oxide layer or metallic zirconium layer interposed between a single-crystal silicon substrate and a lower electrode in the preparation of a printer head for ink jet recording from the single-crystal silicon substrate, the stress applied to the single-crystal silicon substrate due to the difference between the volume change of the single-crystal silicon substrate and the volume change of the lower electrode (and the piezoelectric layer) with the temperature change from high temperature to room temperature and/or from room temperature to high temperature in the process for the preparation of the head can be reduced by the volume expansion of said zirconium oxide layer due to the crystalline phase transition or the oxidation of zirconium to zirconium oxide. Further, the printer head for ink jet recording thus obtained is novel itself. The adhesivity of the zirconium oxide layer to the single-crystal silicon substrate and the lower electrode is good, making it possible to support a piezoelectric layer having a high piezoelectricity. Further, the head drive durability can be enhanced.
The present invention has been worked out on the basis of this knowledge.